Debugging Postfix when using LDAP maps

I know that Postfix is not part of the Core system, however, since kopano doesn’t have a MTA of it’s own we need to use something, and this is really the only forum I have to ask these questions in and this seemed like the most logical location.

So long story short I’m trying to implement a system that would prevent normal users from sending mail to restricted addresses. I want to implement this using two groups:

Restricted Addresses (A group containing users and groups which are restricted)

Restricted Senders (A group containing users who can send to those Restricted Addresses)
I found a nice little write up here which explains how to do it with hash tables. LDAP maps shouldn’t be too much harder… or so I thought.